Teeth whitening or teeth bleaching is the process of lightening the color of human teeth. Whitening is often desirable when teeth become yellowed over time for a number of reasons, and can be achieved by changing the intrinsic or extrinsic color of the teeth enamel. The chemical degradation of the chromogens within or on the teeth is termed as bleaching.
Hydrogen peroxide (H2O2)is the active ingredient most commonly used in whitening products and is delivered as either hydrogen peroxide or carbamide peroxide. Hydrogen peroxide is analogous to carbamide peroxide as it is released when the stable complex is in contact with water. When it diffuses into the teeth, hydrogen peroxide acts as an oxidising agent that breaks down to produce unstable free radicals. In the spaces between the inorganic salts in teeth enamel, these unstable free radicals attach to organic pigment molecules resulting in small, less heavily pigmented
components. Reflecting less light, these smaller molecules create a "whitening effect". There are different products available on the market to remove stains. For whitening treatment to be successful, dental professionals (dental hygienist or dentist) should correctly diagnose the type, intensity and location of the teeth discolouration. Time exposure and the concentration of the bleaching compound, determines the teeth whitening endpoint.